Page 95 - Maths Skills - 7

Comparing Quantities 93

Let’s Attempt

Type I: Finding Profit or Loss Per Cent
Example 1: A man buys 80 pens at ` 10 per pen and sells 50 pens at ` 12 per pen and remaining 30 pens at the
rate ` 9 per pen. Find his gain or loss per cent.

Solution: Cost of 80 pens = ` 80 × 10 = ` 800 Since, total S.P. > total C.P.

Total C.P. = ` 800 Profit = ` (870 – 800) = ` 70
S.P. of 50 pens = ` 12 × 50 = ` 600 \ Profit per cent = Profit × 100
C.P.
S.P. of 30 pens = ` 9 × 30 = ` 270 70 35 3
Total S.P. = ` (600 + 270) = ` 870 = 800 × 100 = 4 = 8 4
3
So, profit % = 8 % .
4

Example 2: Amit bought 3600 bananas at ` 16 a dozen and sold 1850 of them at ` 4 for 2, and remaining at
` 8 for 5. Find his profit or loss per cent.

Solution: Cost of 12 bananas = ` 16

C.P. of 1 banana = ` 16
12
 16 
C.P. of 3600 bananas = `  × 3600  = ` 4800
 12 

S.P. of 2 bananas = ` 4
4
S.P. of 1 banana = ` = ` 2
2
S.P. of 1850 bananas = ` (2 × 1850) = ` 3700
Remaining bananas = 3600 – 1850 = 1750

S.P. of 5 bananas = ` 8
8
S.P. of 1 banana = ` 5

 8 
S.P. of 1750 bananas = `  × 1750 = ` 2800

 5 
Total S.P. = ` (3700 + 2800) = ` 6500

Clearly, total S.P. > total C.P.
Then, Profit = ` (6500 – 4800) = ` 1700

Profit
Profit per cent = C. P. × 100

1700 100×
= 4800 = 35.42
So, Profit% = 35.42%.

Example 3: Find the profit or loss per cent if

(i) C.P. = ` 790; S.P. = ` 870 (ii) C.P. = ` 650; S.P. = ` 610